how to print n number of stars without using loop or condition

Question

Suppose we are giving run time value of n and we want to print the n number of stars in a single row without making use loop and/or condition. How we can do it in java?

With [tag:java-8], not the simplest though: `System.out.println(String.join("*", new String[n+1]).replace("null",""));` — Alexis C., Mar 06 '14 at 18:33
@ZouZou maybe a bit cleaner: `System.out.println(Stream.generate(() -> "*").limit(n).collect(joining()));` — assylias, Mar 06 '14 at 18:45
@assylias That's also nice! May you could simply do: `Stream.generate(() -> "*").limit(n).forEach(System.out::print);` — Alexis C., Mar 06 '14 at 18:50
@ZouZou indeed! Depends on whether you need the string or not. — assylias, Mar 06 '14 at 18:52

score 2 · Accepted Answer · edited May 23 '17 at 11:49

2

Well, here is a neat little trick you could use.

System.out.println(new String(new char[n]).replace("\0", "*"));

Credit for that little snippet goes to user102008 in this thread...

Essentially you are creating a new string using a new char array with [n] indexes. When you create a new array without specifying values, default values are given. The default char is '\0' (the null character). So, by using replace() on the created string you can replace all instances of that character (the number of which you have already specified) with whatever char/String you like.

edited May 23 '17 at 11:49

Community

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answered Mar 06 '14 at 18:21

Rudi Kershaw

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What's the point of answering by copying from a duplicate? – s.bandara Mar 06 '14 at 18:24
@s.bandara - They wanted to know and they might not have found it otherwise. Would you have rated it up if I hadn't given credit to it's creator? – Rudi Kershaw Mar 06 '14 at 18:26
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As this is likely homework related, I would downvote it either for being unhelpful to the OP or [code trolling](http://meta.codegolf.stackexchange.com/questions/746/code-troll-rules) (outside of code golf.SE). – Mar 06 '14 at 18:39
@MichaelT - How exactly is that code trolling? It does exactly what they ask in one line, it's concise, fairly easy to read and has little to no overheads. By the definition you just linked it is literally the opposite of code-trolling. – Rudi Kershaw Mar 06 '14 at 18:45
That you @RudiKershaw i got it. – Rajnish Pandey Mar 07 '14 at 01:17

Richard Miskin · Answer 2 · 2014-03-06T18:35:54.667

2

You can use recursion to print out stars with the following code:

public class RecursiveStars {

    public static void main(final String[] args) {
        printStar(5);
    }

    /**
     * 
     * @param i
     *            the number of stars to print
     */
    private static void printStar(final int i) {
        if (i > 0) {
            System.out.print('*');
            printStar(i - 1);
        }
    }

}

If you want to avoid the condition you can still use recursion but break out of the loop by triggering an ArithmeticException. (This is horrible, but does meet your requirement.)

public class RecursiveStars {

    public static void main(final String[] args) {
        try {
            printStar(5);
        } catch (final ArithmeticException e) {
            // Ignore
        }
    }

    /**
     * 
     * @param i
     *            the number of stars to print
     */
    private static void printStar(final int i) {
        final int triggerException = 1 / i;
        System.out.print('*');
        printStar(i - 1);
    }
}

edited Mar 06 '14 at 18:35

answered Mar 06 '14 at 18:26

Richard Miskin

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7
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You include condition. – T8Z Mar 06 '14 at 18:30
+1 for exceptional solution :D – Not a bug Mar 06 '14 at 18:36
@T8Z I've added a modified example without the condition - not sure I'd recommend it other than to prove a point. – Richard Miskin Mar 06 '14 at 18:37
@T8Z No need to apologise - I'd missed part of the original question. – Richard Miskin Mar 06 '14 at 18:44
I think recursion is another form of looping. – Rajnish Pandey Mar 06 '14 at 18:49
@user1969029 recursion and looping can both be used to solve similar problems, but they are not identical. I've not made use of any Java loop constructs. – Richard Miskin Mar 06 '14 at 19:17

how to print n number of stars without using loop or condition

2 Answers2